This invention relates to communications systems that provide a redundant module for interfacing with communication lines in case of failure of a primary interface module.
Conventional communications systems (e.g., telecommunications systems) typically include multiple communication lines that are connected to corresponding primary interface modules for receiving data on the lines. The interface modules are "field replaceable" for servicing and/or replacement in case of failure. The communications system also includes one or more spare (i.e., redundant) modules for connection to the appropriate communication lines in case of failure or servicing of a primary interface module. One known scheme for providing this redundancy uses a dedicated switching module or subsystem to detect the failure of a primary module and connect the spare module in its place to the corresponding communication line.